Terminal for wires of electric circuits



S. ANTHONY.

TERMINAL FOR WIRES OF ELECTRIC CIRCUITS.

I APPLICATION FILED OCT. 28, I918.

Patented Nov. 1, 1921.

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cans stares STANLEY ANTHONY, 0F BOSTON, MASSACHUSETTS. I

TERMINAL FOR WIRES 014 ELECTRIC CIRCUITS.

Specification of Letters Patent.

Patented Nov. 1, 1921.

Application filed October 28, 1918. Serial No. 259,962.

To all whom it may concern:

Be it known that I, STANLEY ANTHONY, a citizen of the United States, residin at Boston, county of Suffolk, State of assachusetts, have invented an Improvement in Terminals for Wires of Electric Circuits, of which the following description, in connection with the accompanying drawing, is a specification, like characters on the drawing representing like parts.

This invention relates to screws used for attaching the wires of electric circuits to terminal members, and has for its object to provide a novel screw for this purpose which is constructed so that the tightening of the screw will act to cause the wire connected thereto to be drawn tightly about the shank of the screw.

In connecting electric wires to terminals it is a common practice to use a screw having a head with a fiat. under face and to wrap or bend the end of the wire about the shank of the screw and then tighten the screw so as to clamp the wire between the head of the screw and the other element of the terminal. Where the under face of the head of the screw is flat, the tightening of the screw is very apt to crowd the loop in the end of the wire outwardly away from the shank of the screw and frequently the wire is crowded so far toward the periphery of the screw head that the latter does not properly hold the wire so that a broken connec tion is likely to result. This is especially truewhere the wire is composed of a plurality of strands as the wires for many electrical circuits are because usually the diameter of the stranded wire is such relative to the size of the screw head that the exterior diameter of the loop of wire is about the same as that of the screw head, and the tightening of the screw serves to flatten'the stranded wire and thus crowd the outer strands of the bend outwardly beyond the periphery of the screw. This crowding action is augmented by the friction between the under face of the screw head and the wire as the screw is turned.

My invention provides a novel form of screw which is constructed so that the operation of tightening the screw will result in forcing the portion of the -wire underneath the head of the screw toward the shank of the screw. I accomplish this by makin the under face of the screw head conca e from the peripheral portion toward the center so that the point of junction between the shank of the screw and the head at the central part of the head is situated above the plane of the peripheral portion of the under face of said head.

In order to give an understanding of my invention, I have illustrated in the drawings a selected embodiment thereof which will now be described, after which the novel features will be'pointed out in the appended claims.

In the drawings, Figure 1 is a vertical section through a terminal to which a wire 15 secured by my improved screw;

Flg. 2 is a section on the line 22, Fig 1;

Fig. 3 is a view similar to Fig. 2 showing the construction'now commonly used.

In the drawings 11 indicates a binding post or some other fixed element to which the electric wire 7 is to be secured, and the screw embodying my invention is indicated generally at 14. This screw is provided with the head 4'which is shown as having the screw-driver slot 16 therein and also'is provided with the screw-threaded shank 13 adapted to screw into a recess in the terminal member 11. The terminal member 11 is shown as having the usual flat clamping face, 12. The under or clamping face 15 of the head of the screw is concave from the peripheral portion toward the center, and as 'a result the clamping face 15 of the screw head will gradually diverge from the clamping face 12 of the terminal member from the periphery of the screw head toward the center. Further,the point of junctiombetween the shank 13 and the screw head will be situated above the peripheral edge of the under face 15.

In connecting the wire 7 to a terminal by means of my improved screw, the end of the.

wire will be formed into a loop 6, as shown 1n Fig, 2, and the shank 13 of the screw is then passed through the loop and screwthreaded into the terminal member 11. As the screw is tightened the under clamping face 15 of the screw head 4 will engage the loop 6 and because of the upward inclination of-said face from the peripheral edge toward the center, said clamping face will tend to crowd the loop 6 ofthe wire toward the center and into firm contact with the shank 13 of the screw. The screw will have no tendency to force the loop 6 outwardly toward the periphery of the head as is the 

